Brown Bullhead Catfish come from North America. You can find them in the eastern and middle parts of the United States and southern Canada. For hundreds of years, people there, like the Native Americans, ate them. They were an important part of the local natural environments. These fish were taken to Europe a long time ago, in the 1800s. From there, they spread to many other places around the world.
Brown Bullhead Catfish were brought to New Zealand in the 1870s. People wanted them for fun fishing and to eat. They were brought because they are tough fish and can live well in many different freshwater places. However, some escaped or were let go into the rivers and lakes. They started making families there and became harmful fish that don't belong here.
These catfish can grow up to 50 centimeters long. They can weigh as much as 1.8 kilograms.
They have a strong, long body. Their skin is smooth and does not have scales, like many other fish.
Their color is usually dark brown or black on top. Their bellies are a lighter color.
They have whisker-like feelers around their mouth. These feelers help them explore and find food in the water.
Female catfish build nests in shallow water that has many plants. This is where they lay their eggs.
Male catfish make the eggs ready to grow. These eggs then hatch into tiny baby fish in about a week.
The tiny baby fish eat very small creatures. As they get older, they slowly start to eat different kinds of food.
Brown Bullhead Catfish eat both plants and animals. They munch on algae, water plants, bugs, small crabs, tiny fish, and even bits of dead stuff. These fish can easily change what they eat, which helps them live well in many different water places like rivers and lakes. This also helps them become harmful fish that don't belong here in many places, such as New Zealand.
They eat algae and water plants.
They find bugs, small crabs, and snails using their whiskers.
They also hunt and eat smaller fish, taking food away from fish that naturally live there.
In New Zealand, Brown Bullhead Catfish are seen as a harmful fish that doesn't belong there. They cause big problems for the natural environments where local plants and animals live. These catfish often live in calm rivers, lakes, and ponds. They stir up the mud at the bottom, pull up water plants, and take food and homes away from the fish that naturally live there. This makes the natural homes worse for other creatures.
"These catfish can live in many different water places because they are tough and can get used to different conditions. They eat other animals and use their long whiskers to find food like bugs, small crabs, and little fish at the bottom of the water. They even eat Koura (New Zealand crayfish) and other special local animals. They can live in dirty water and make it even dirtier when they look for food, stirring up the mud. A female catfish can have up to 6,000 babies in one year!"
— Bay of Plenty Regional Council
Catfish stir up mud and pull up underwater plants. This ruins important homes for the animals and plants that belong here.
They take food and homes from fish that belong here. This means there are fewer kinds of plants and animals in our natural fresh water.
Catfish eat Koura (freshwater crayfish) and other animals that are very special to our culture.
When catfish eat from the bottom, they stir up mud and dirt. This makes the water dirty and cloudy.
Brown Bullhead Catfish can live in dirty water. They can survive in many different places, which means they can start living in almost any river, lake, or pond across New Zealand.
They eat other animals and use their whiskers (called barbels) to find food at the bottom. This makes them very good hunters. Since they also have many babies, they can grow fast and spread quickly in freshwater natural environments.
They can have many babies quickly.
They can get quite big!
Efforts to control Brown Bullhead Catfish populations in New Zealand include various methods aimed at reducing their impact on native ecosystems. These measures are essential to protect native species and restore the balance of freshwater habitats.
Targeted trapping programmes to remove catfish from affected waterways
Use of specialised nets to capture catfish populations in lakes and ponds
Altering environments to make them less suitable for catfish whilst supporting native species
Ongoing surveillance to track populations and assess control effectiveness
Where do Brown Bullhead Catfish originate from, and how long have they been part of local ecosystems there?
Answer: They originate from eastern and central United States and southern Canada, where they have been integral to ecosystems for centuries.
When and why were Brown Bullhead Catfish introduced to New Zealand?
Answer: They were introduced in the 1870s for recreational fishing and as a food source.
What are the ecological concerns associated with their establishment in New Zealand?
Answer: They disturb sediment, uproot vegetation, outcompete native fish, prey on taonga species, and contribute to water quality decline.
Describe their physical characteristics and growth potential.
Answer: They grow up to 50cm and 1.8kg, with stout bodies, smooth scaleless skin, dark brown or black coloration, and distinctive barbels.
What impact do they have on freshwater ecosystems and what control measures are being taken?
Answer: They degrade habitats and outcompete native species. Control measures include trapping, netting, and habitat modification.
This harmful fish doesn't belong here and is causing trouble for New Zealand's natural water places.